1. Field of the Invention
The present invention relates to a hydrogen gas analyzer for determining the concentration of hydrogen gas contained in a sample and, more particularly, to a hydrogen gas analyzer having an improved delivery or feed system wherein a sample gas and an additive fuel gas are introduced into a catalytic combustion tank and combusted to measure the water byproduct produced.
2. Description of Related Art
Apparatus for measuring the concentration of hydrogen (H.sub.2) gas contained in a sample, such as combustion exhaust gas, is known in the prior art. The manner in which the concentration of gas is measured through an analysis of the byproduct of water output from a combustion tank is also known.
Referring to FIG. 2, a schematic illustration of a prior art hydrogen gas analyzer is disclosed. A catalytic combustion tank 1 containing an oxidizing catalyst agent is connected to a sample gas supply passage 4 and an additive or supplemental fuel gas supply passage 5, both being provided with restrictive capillaries 2 and 3 for regulating the respective flow rates. A junction or Y-connector 7 can be used for connecting the respective gas supply passageway 4 and supplemental fuel gas supply passageway 5 to the catalytic tank 1. A sample gas SG, such as a combustion exhaust gas, and a supplemental fuel gas J, such as air or oxygen, can be introduced into the catalytic tank 1 to combust the sample gas SG and produce a resultant byproduct of water (H.sub.2 O) in the resultant output gas G. The amount of water can be quantitatively determined by means of a water meter 6, which is known in the art, to measure the concentration of the hydrogen gas contained in the combustion exhaust gas. The water meter 6 can comprise, for example, an infrared gas analyzer.
A problem can occur if the combustibility of the additive fuel deteriorates, since H.sub.2 (hydrogen), CO (carbon monoxide), and HC (hydrocarbons) are also frequently contained in the combustion exhaust gas produced by the combustion of petroleum refinery fuels. If a significant amount of these other components are contained in the sample gas, it is possible to generate a byproduct of H.sub.2 O through the combustion of the HC coexisting in the sample gas SG. As a result, a subsequent measurement by a hydrogen gas analyzer can produce a quantitative determination of H.sub.2 O by means of the water meter 6 that would not only include H.sub.2 O resulting from combustion of H.sub.2, but also H.sub.2 O resulting from the combustion of the HC. As a result, the measurement accuracy can be directly affected. One suggested solution to this problem is based on the fact that H.sub.2 is highly combustible and can be combusted at temperatures lower than HC. Accordingly, an attempt is made to lower the temperature of the catalytic tank 1 so it would be difficult to combust the HC components.
An additional problem, however, can occur because other components in the sample gas SG, such as CO, can also be burned together with the H.sub.2 so that the combustion heat, proportional to the concentration of CO and H.sub.2 generated by their combustion, can effectively raise the temperature of the catalytic tank 1 to the point that the HC components can also be combusted. As a result, the accuracy of the measurement of the water meter 6 is affected.
There have been suggestions that the sample gas SG should be diluted with an assistant or additive fuel gas J, but this can have the effect of reducing the concentrations of H.sub.2 and CO in the sample gas SG so that the combustion heat produced by their combustion is reduced and the temperature rise of the catalytic tank 1 is reduced. In these circumstances, the combustion of the HC components are minimized. A problem still exists, however, in that the signal-to-noise (S/N) ratio in the water meter 6 is further deteriorated due to the dilution of the sample gas SG. Accordingly, the accuracy of the measurement is further reduced.
Accordingly, there is still a desire in the prior art to try to improve the analysis of a sample gas in which the concentration of hydrogen is desired to be determined.